Woodell



March 17, 1964 R. WOODELL BULKY YARN 5 Sheets-Sheet 1 Filed Oct. 24,1962 INVENTOR RUDOLPH WOODELL ATTORNEY March 17, 1964 R. WOODELL BULKYYARN 3 Sheets-Sheet 2 Fl Z Filed Oct. 24, 1962 INVENT OR RUDOL'PHWOODELL ATTORNEY v March 17, 1964 R. WOODELL 3,124,926

BULKY YARN Filed Oct. 24, 1962 3 Sheets-Sheet 3 INVENTOR RUDQOLPHwooozu.

ATTORNEY United States Patent 3,124,926 BULKY YARN Rudolph Woodell,Richmond, Va, assignor to E. I. du Pont de Nemours and Company,Wilmington, Del a corporation of Delaware Filed Oct. 24, 1962, Ser. No.233,205 5 Claims. (Cl. 57140) This invention relates to a novel anduseful bulky yarn composed of continuous filaments and a process andapparatus for its production. This is a continuation-in-part of mycopending application Serial No. 757,230, filed August 26, 1958.

Almost all synthetic fibers are produced most easily as continuousfilaments. Continuous filament yarns are much stronger than staple fiberyarns because of the absence of loose ends but, because of their extremeuniformity and lack of discontinuities, conventional continuous filamentyarns are much more dense than their staple counterparts. The filamentslie close together in the yarn, and adjacent strands of continuousfilament yarn in fabrics are closely and evenly spaced. It would bedesirable to provide a continuous filament yarn which retains itsstrength characteristics and which has the lightness and coveringeffectiveness, as well as interesting decorative surface effects,commonly achieved with yarns spun from staple fibers.

U.S. Patent 2,783,609, issued to A. L. Breen on March 5, 1957, disclosesone process for converting continuous filament yarn into bulky yarnwhich, when woven into fabrics, gives effects similar to those obtainedwith staple yarns. In this process the continuous filament yarn ispassed through a turbulent stream of air or other gas Where thefilaments are looped and entangled to give the desired bulk. While thisprocess produces very desirable bulky continuous filament yarns, itobviously requires that the yarn be prepared in the conventional manner,and then be subsequently subjected to a second operation in order toobtain the final product. In addition, fabrics made from this yarn havea uniform surface appearance and are, therefore, not as susceptible tothe formation of non-uniform, decorative surface effects.

Decorative surface effects in fabrics have frequently been achieved bythe use of slub yarns, i.e. yarns having bulky protrusions at intervalsalong their length. The slub yarns of the prior art, however, tend to beuniform with regard to the size and spacing of the slubs. Furthermore,known processes which provide slub yarns do not readily yield slubs ofconsiderable length, i.e. four to five inches.

It is an object of this invention to provide a novel and useful bulky,continuous filament yarn. Another object is to provide a novel bulkyyarn which may be used to produce fabrics having unique, decorativesurface effects.

Another object is to provide a process and apparatus for I producing theyarn. Other objects will become apparent from the specification andclaims.

According to this invention, there is provided a yarn composed ofcontinuous filaments in which the filaments are looped and entangled atintervals throughout the filament length to form bulky sections in theyarn, the bulky sections varying in a random fashion with respect tolength, bulkiness and spacing along the yarn, the minimum variation inlength being at least five-fold and the minimum variation in bulkinessbeing at least two-fold, ie the longest bulky section is at least fivetimes the length of the least bulky section and the average diameter ofthe most bulky section is at least twice the average diameter of theleast bulky section. The variations in bulkiness and in the length ofthe bulky sections which result from this treatment, as well as theoccurrence of short non-bulky sections of varying length, enhance thedecorative effects obtained when the yarn is woven into fabric.

This novel bulky yarn is produced by feeding a plurality of continuousfilaments into a rapidly moving stream of liquid, introducing thefilaments and liquid into a chamber, imparting a turbulent swirlingmotion to the liquid containing the filaments to carry the filaments ina generally circular path within the chamber and to entangle thefilaments, and drawing the filaments away under low tension.

The feed yarn is any continuous multifilament yarn from a suitablesource, such as a conventional package, and is preferably supplied atsubstantially zero twist. The feed filaments can be introduced directlyfrom a wetspinning operation, in which case an effective processcomprises extruding a filament-forming solution through a spinneretassembly into a coagulating solution to form a plurality of filaments,introducing (preferably concurrently) the newly-formed filaments into arapidly moving stream of liquid, preferably a coagulating liquid,whereby the filaments are carried into a chamber, imparting a turbulentswirling motion to the liquid to carry the filaments in a generallycircular path, preferably about threequarters of the way around thechamber, and to entangle the filaments, and thereafter drawing thefilaments away under low tension.

' According to one embodiment of the invention, a novel blended bulkyyarn is provided by introducing other filaments, preferably syntheticfilaments, into the rapidly moving stream of coagulating liquid alongwith the newlyformed filaments.

Apparatus utilizing wet-spinning for producing the yarns comprises aspinneret, means for supplying a filament-forming solution to thespinneret, a conduit through which the filaments pass after extrusionfrom the spinneret, means for forcing liquid, preferably a coagulatingliquid through the conduit along with the filaments, a chamber situatedat the end of the conduit to receive the filaments and coagulatingliquid, the chamber having an outlet for the liquid and filaments andmeans for imparting to the liquid in the chamber a turbulent swirlingmotion. Apparatus suitable for processing pnespun yarn differs only inthat the spinneret and means for supplying filament-forming solution arereplaced by conventional means for feeding yarn to the conduit from apackage or other convenient source.

FIG. 1 is a schematic isometric drawing of a typical form of apparatussuitable for performing the process of this invention.

FIG. 2 is a transverse cross-section of the swirl pool shownschematically in FIG. 1.

FIGURE 3 is a cross-section along the line 33 of FIGURE 2.

FIGURE 4 is a magnified partial longitudinal side view 1 of a yarnembodying the present invention.

FIGURE 5 is a less magnified view of the yarn of FIGURE 4.

In the apparatus shown in FIGURE 1, a filament-forming solution isextruded through spinnerset 1 into a coagulating and regenerating bath 2which partially fills spin box 3. The freshly formed filaments 4 arecarried downwardly through spinning tube 5- by a rapidly moving streamof the coagulating bath which is forced through the tube 5 by thepressure head of the coagulating and regenerating bath which surroundsspinneret 1 and entrance of spinning tube 5. The bath carrying thefilaments is discharged into swirl pool 6 and is given a swirling motionby a second stream of bath from container 7 fed from spin box 3 andthrough conduit =13. This bath is jetted through conduit 14 and orifice8 (as shown in FIGURE 3) at an angle with respect to the exit ofspinning tube of about 90. The velocity of the bath through the orifice'8 is adjusted to impart a swirling motion of sufiicient intensity todeflect the filaments and carry them in a generally circular path aboutthreequarters of the way around the chamber (as shown in FIGURE 3)before being discharged through the opening 9 in the bottom of thechamber. The yarn is discharged from the chamber 6 into the dischargetube 11 from which it passes for a distance through the bath 20 incontainer 12 over a converging guide 16 and through various other guides17 and 18, and finally to a con ventionally centrifugal spinning bucket(not shown) where the yarn is wound into a cake in the conventionalmanner.

A transverse enlarged cross-section of the container or swirl pool; 6 ofFIGURE 1 is shown in FIGURE 2.

FIGURE 3 shows the normal path of filament movement in swirl pool 6. Theswirl pool 6 has an inner opening, shown in FIGURE 3 as bowl-shapedchamber 6. The exit of the spinning tube 5 leads into chamber 6off-center of the axis of revolution of the chamber and orifice 8 of thebath jet is located in line with the exit of spinning tube 5, at anangle of about 90 with its axis. Opening 9 in the bottom of the chamberleads into discharge tube 11, which is curved at a 90 angle outside thecontainer into the bath 20. Pin 10 holds the discharge tube securely inplace.

EXAMPLE -I Viscose containing 6.25% recoverable cellulose and 5.75%alkali, calculated as. sodium hydroxide, is prepared in the conventionalmanner from cotton linters pulp using- 30% carbon disulfide based on theair dry weight of the pulp. The viscose is filtered, deaerated, ripenedto a salt index of 4.3 and a viscosity of about 5.5 poises and extrudedthrough a spinneret having 120 holes of 0.0025 inch diameter into acoagulating and regenerating bath containing 9.5% sulfuric acid, 19.25%sodium. sulfate, 3.5% zinc sulfate, 2.0% glucose and maintained at atemperature of 55 C.

The freshly formed filaments are passed through a spinning tube of 7 mm.diameter for a distance of 9 inches by a rapidly moving stream ofcoagulating bath which is forced through the tube by maintaining a bathhead of about 9 inches in a container which surrounds the, spinneret andtube entrance. The bath carrying the filaments is discharged into a bowlshaped chamber 3 inches in diameter and 2.5 in. deep. A second stream ofbath is jetted through an orifice of 0.1875 inch diameter under apressure head of about 115 inches of bath. The second bathstream isjetted into the first bath stream carrying the unconverged filaments atan angle of about, 90 with respect to the exit of the spinning tube.

The velocity of the bath through the orifice is adjusted to impart aswirling motion of sufficient intensity to deflect the filaments andcarry them in a generally circular path about three-quarters of the wayaround the chamher before being discharged through the opening in thebottom of the chamber. The yarn is then carried for a distance of about7- inches through a tube of 12 mm. diameter. The yarn is then passed forsix inches through. a coagulating and regenerating bath, of thecomposition given above, over a Y-guide and then for a further distanceof 33 inches through the bath where it is confined by means. of tworoller guides. The yarn is then passed under a hook guide, up to andaround a feed wheel having a peripheral speed of 50 yards per minute andthen downwardly into a centrifugal spinning bucket where the yarn, whichhas an average denier of 3 20, is wound into a cake in the conventionalmanner.

The yarn is purified, dried and wound into cones in the conventionalmanner. The yarn contains bulky sections varying in length from about /2inch to about 6 inches. The average diameter (bulkiness) of the mostbulky sections is at least 3 times that of the least bulky sections. Thelonger bulky sections vary appreciably in bulkiness along their length.The non-bulky sections vary in length from about A inch to about 3 to 4inches to give a random spacing of the bulky portions of the yarn. Whenthe yarn is woven into a plain weave fabric the fabric has the desirabletexture of a, fabric woven from spun yarn and in addition displays alinen-like effect due to the random variation in bulkiness of the yarn.Very desirable linen-like fabric is obtained when the above yarn is usedas a filling in a plain weave fabric with a cotton warp.

EXAMPLE II Viscose containing 6.25% recoverable cellulose and 5.75%alkali, calculated as sodium hydroxide, is prepared in the conventionalmanner from cotton linters pulp using 30% carbon disulfide based on theair dry weight of the pulp. The viscose is filtered, deaerated, ripenedto a salt index of 4.0 and a viscosity of about 55 poises and extrudedthrough a spinneret having 120 holes of 0.0035 inch diameter into acoagulating and regenerating bath containing 9.5% sulfuric acid, 19.25%sodium sulfate, 3.5% zinc sulfate and 2.0% glucose, the temperature ofthe bath being 55 C.

The freshly formed filaments are carried downwardly through a spinningtube of 7 mm. diameter and 14 inches length by a rapidly moving streamof coagulating bath which is forced through the tube by maintaining thebath level about 1 to 2 inches above the tube entrance in the containerwhich surrounds the spinneret and tube entrance. The bath carrying thefilaments is discharged into a bowl-shaped circular chamber 2% inches indiameter and having an average depth of 1 inches. A second stream ofbath is jetted through an orifice of 0.1875 inch diameter into the firstbath stream carrying the unconverged filaments, the angle of the bathjet with respect to the spinning tube exit being about The velocity ofthe bath through the orifice is adjusted to impart a swirling motion ofsutficient intensity to deflect the filaments and carry them in agenerally circular path about three-quarters of the way around thechamber before being discharged through the opening in the bottom of thechamber. The yarn is discharged from the bowl into a tube of 13millimeters inside diameter and an over-all length of 7 inches. Afterleaving the tube which is submerged in coagulating bath, the yarn ispassed for a distance of 6 inches through the bath, over a Y-guide, andthen for a further distance of 33 inches through the bath where it isconfined by means of a roller guide. The yarn is then passed under ahook guide, up to and around a feed Wheel having a peripheral speed of9.0 yards per minute and then downwardly into a centrifugal spinningbucket where the yarn, which has an average denier of 300, is wound intoa cake in the conventional manner.

The yarn is purified, dried and wound into cones in the conventionalmanner. The yarn contains bulky sections varying in length from about /2inch to 6 inches. The average diameter of the most bulky sections isjudged to be at least 3 times that of the least bulky sections. Thenon-bulky sections vary in length from about /2 inch to about 3 to 4inches to give a random spacing of the bulky sections. The longer bulkysections vary appreciably in bulkiness along their length. When the yarnis woven into a plain weave fabric, the fabric has the desirable textureof a fabric Woven from spun yarn and in addition, displays a linen-likeeffect due to the random variation in bulkiness of the yarn. Verydesirable linen-like fabric is obtained when the above yarn is used as afilling in a plain weave fabric with a cotton warp.

EXAMPLE III Example I is repeated except that a zero twist polyethyleneterephthalate yarn is fed into the top of the spinning tube, combinedwith the rayon filaments, and carried through the process. By thismeans, the rayon and polyethylene terephthalate filaments areintermingled to produce a bulky blended yarn. The yarn is similar ingeneral appearance to the yarn of Example II. Various deniers of rayonare combined with the various deniers of polyethylene terephthalate yarnto produce the combinations shown in Table I below:

Table l Rayon (Total Polyethylene Percent Polydenier) terephthalateethylene tere- (Total denier) phthalate When the 300 denier yarncontaining 23% polyethylene I EXAMPLE IV Apparatus similar to that usedin Example II is set up except that a spinneret is not used and water isused as the liquid bath instead of a coagulating bath. A 100 denier, 68filament, twist yarn, of polyethylene terephthalate including 2 molpercent of the sodium salt of poly(sulfisophthalate), the filamentshaving a trilobal cross-section, is fed to the spinning tube of thespinning box. The yarn, as it comes from the supply package, is ledthrough a tension gate and is passed through a spinning tube of 0.25inch diameter and 14 inches in length. The yarn is fed to thebowl-shaped chamber by the rapidly moving stream of water, which isforced by gravity through the tube by maintaining the bath I level inthe spin box about 1 to 2 inches above the tube entrance. The tensiongate is adjusted to supply a low level of tension to the yarn so as tominimize tension variations resulting from take-off from the supplypackage. The water passing down the spinning tube carries the filamentsto a bowl-shaped circular chamber 2.875 inches in diameter and having anaverage depth of about 1.5 inches. A second stream of water is carriedfrom container 7, which is located about 5 inches above the height ofthe water in container 12, and is jetted through orifice 8 having adiameter of 0.1875 inch into the first bath stream carrying theunconverged filaments, the angle of the bath jet with respect to thespinning tube exit being about 90 degrees.

The velocity of the water through orifice 8 is adjusted to impart aswirling motion to the water in the bowlshaped chamber but not ofsufficient velocity to cause the water to overflow from the chamber. Theswirling action is of sufficient intensity to deflect the filaments andcarry them in a general circular path about of the way around thechamber before they are discharged through the 0.5 inch opening in thebottom of the chamber. The yarn then passes from the bowl into tube 11of 0.375 inch inside diameter and having a length of about 6 inches.After leaving the tube which is submerged in the water in container 12,the yarn passes for a distance of about 20 inches through the water andis led through a pigtail guide before exiting from the bath. Since thewindup speed is less than the speed at which the slubbed yarn isdischarged from tube 11, additional entanglement of the yarn occursbetween the exit of tube 11 and the pigtail guide. After exiting fromthe bath, the yarn passes as does the yarn having the bulky portions.

around a convenient snubbing device, such as a spool guide, in order toapply a slight tension between the yarn and the windup. After passingover the spool guide, the yarn is led to the windup where it is woundinto a package in a conventional manner at a windup speed of 27 yardsper minute.

The yarn, which has an average denier of 251.8, contains bulky sectionsvarying in length from 0.25 to 28 inches with an average length of 3.8inches. The bulky sections, of which there are 200 to 230 per yards,have a maximum denier of 800. The interval between the bulky sectionsvaries from 1 to 72 inches with an average of 14 inches.

When the above experiment is repeated using an aqueous spin-finishemulsion, essentially equivalent results are obtained.

EXAMPLE V Example IV is repeated except that the yarn is wound up at aspeed of 48 yards per minute. At this windup speed the bulky sectionsare formed within the bowl shaped chamber and no additional entanglementoccurs in bath 21.

The yarn, which has an average denier of 113.1, contains bulky sectionsvarying in length from about 0.5 to 12 inches with an average length ofabout 3 inches. The bulky sections have a maximum denier of 450 andthere are 87 to 93 bulky sections per 100 yards. The interval betweenthe bulky sections varies in length from 6 to 144 inches with an averageof 37 inches.

EXAMPLE VI Example V is repeated except that a 40-denier, 27 filamentyarn is added as a support yarn. The filaments of the support yarn havea trilobal cross-section and are melt spun from a polyethyleneterephthalate copolymer having 2 mol percent of the sodium salt ofpoly(sulfisophthalate).

The support yarn is removed from the supply package and passes over aguide and is then fed to the vortex of the whirlpool and follows thesame path to the windup The component of the combined yarn that containsthe bulky portions is the same as that of Example V. The yarn containingthe bulky portions and the support yarn are well combined. The averagedenier of the combined yarn is 152.8.

Any filament-forming solution is suitable for treatment in accordancewith this invention. Viscose solutions which are commonly used in thespinning of textile rayons are particularly satisfactory. In addition,cuprammonium solutions of cellulose and other filament-forming solutionssuch as cellulose acetate and polyacrylonitrile solutions,conventionally used in wet spinning processes, can be satisfactorilyemployed in the process of this invention. Likewise, any of thecoagulating liquids commonly used in wet spinning process may besatisfactorily employed. In the viscose process, baths containing 4-12%sulfuric acid, sodium sulfate and other metal sulfates such as zincsulfate are commonly used and are suitable.

. Any other continuous filament feed from a different source may beintermingled with the wet-spun filaments to provide the novel blendedbulky yarn, or can entirely replace wet-spun filaments to produce bulkyyarn prod ucts of this invention. For example, yarns comprisingpolyesters, such as polyethylene terephthalate, polyamides such as theconventional nylons, dry-spun acrylonitrile polymers, polyurethanes,poly (vinyl chloride) polymers and copolymers thereof are suitable.

The velocity of the bath in the conduit leading away from the spinneretor other source of feed yarn may be adjusted to any speed depending onthe processing speed desired. In commercial practice, the velocity ispreferably fairly high, i.e., 40 yds./min. or higher, since thefilaments are carried solely by the bath, the higher the velocity, thehigher the processing speed, of course. Also, in the event that theswirling motion in the chamber at the end of the tube is imparted by theuse of a baffle which directs the bath flow towards the wall of acircular chamber, then the velocity should be sufiiciently high toprovide an adequate swirling motion within the chamber. Preferably, theswirling motion should be adjusted to carry the filaments aboutthree-fourths of the way around the chamber, that is, they traverseabout three-quarters of a circle before being discharged from thechamber into the exit tube.

The turbulent swirling motion in the chamber at the end of the conduitmay be created in a number of ways. As mentioned above, a suitablebafiie may be placed so that the bath stream entering the chamber isdeflected around the wall of the chamber, the chamber in this case beingsubstantially circular in shape. Another method of imparting therequired turbulent swirling motion is by using an air jet, which ispreferably placed near the point where the bath, along with thefilaments, enters the chamber and at a transverse angle to the bathconduit, preferably about 90. The preferred method of imparting theturbulent swirling motion, however, is by means of a stream of bathwhich is jetted into the bath stream carrying the filaments. Preferably,the second bath stream is jetted into the first stream by means of anorifice located adjacent to the point of entrance of the first bathstream and positioned so that the second bath stream travels in atransverse direction to that of the first bath stream to deflect thefilaments toward the side of the chamber.

In drawing the yarn away from the swirl-chamber, high tensions should beavoided to prevent the entanglements in the filaments from beingpartially or completely removed. The tensions normally encountered whenusing ordinary guides will cause no difficulty.

The swirl-chamber may be of any size and shape and may be varieddepending on the processing conditions employed. The chamber is,however, preferably bowl shaped and, for the processing of most textileyarns, is from 3 to 5 inches in diameter. The outlet for the bath andyarn may be rounded and is preferably centered in the bottom of thebowl, but this may be varied to some extent without harm, e.g., it maybe located at one side of the chamber.

The random variations in the spacing, the length and the bulkiness ofthe bulky portions of the yarns of this invention result in fabricshaving highly attractive surface effects. Such fabrics are highlydesirable for use in such applications as wearing apparel and draperymaterials.

Since many different embodiments of the invention may be made withoutdeparting from the spirit and scope thereof, it is to be understood thatthe invention is not limited by the specific illustrations except to theextent defined in the following claims.

I claim:

1. A blended bulky yarn comprising continuous wetspun syntheticfilaments intermingled with other continuous synthetic filaments, saidyarn being looped and entangled at spaced intervals along the yarnlength to form spaced bulky sections in the yarn, said bulky sections ibeing separated from each other by an axial distance varying incompletely random fashion and the bulkiness of said sectionscontinuously varying in completely random fashion, the minimum variationin length being at least five-fold and the minimum variation inbulkiness being at least two-fold, the yarn in said sections separatingsaid bulky sections comprising substantially straight filaments incompact even alignment.

2. The blended yarn of claim 1 wherein the wet-spun filaments compriserayon and the other continuous fila ments comprise polyethyleneterephthalate.

3. A cross-dyed fabric of unusual appearance made from a yarn comprisingcontinuous wet spun synthetic filaments intermingled with othercontinuous filaments of a different type looped and entangled atlaterally aligned intermittent intervals along their length to formrandomly spaced bulky sections along the yarn length, said bulkysections continuously varying in completely random fashion as to sectionlength and bulkiness, the minimum variation in length being at leastfive-fold and the minimum variation in bulkiness being at leasttwo-fold, the axial lengths between said bulky sections comprisingsubstantially smooth, uncrimped closely aligned filaments, said bulkysections and lengths of aligned filaments cooperating to produce in saidfabric a linen-like appearance with uneven roughened areas of varyingsize creating splash-like effects completely randomly scatteredthroughout said fabric corresponding to said bulky sections of saidyarn.

4. The fabric of claim 3 in which the wet spun yarn filaments are of arayon composition and the differing filaments are composed ofpolyethylene terephthalate.

5. A bulky yarn comprising continuous filaments each looped andentangled at laterally aligned intermittent intervals throughout theyarn length to form spaced bulky sections in the yarn, the spacingbetween said bulky sections varying in a random fashion, said bulkysections continuously varying in completely random fashion as to lengthand bulkiness, the minimum variation in length being at least five-fold,and the minimum variation in bulkiness being at least two-fold, theaxial length between said bulky sections comprising continuoussubstantially unbulked filaments in a compact constant denier arrangement.

References Cited in the file of this patent UNITED STATES PATENTS1,122,231 Caldwell Dec. 22, 1914 1,165,819 Ware Dec. 28, 1915 2,000,951Hodson May 14, 1935 2,255,246 Fraser Sept. 9, 1941 2,451,504 Mayo Oct.19, 1948 2,700,866 Strang Feb. 1, 1955 2,783,609 Breen Mar. 5, 19572,854,814 Burkholder Oct. 7, 1958 2,964,900 Hicks Dec. 20, 19602,999,351 Davenport et a1 Sept. 12, 1961 3,041,812 Marshall July 3, 19623,042,482 Woodell July 3, 1962 3,047,932 Pittman et al. Aug. 7, 1962FOREIGN PATENTS 776,410 Great Britain June 5, 1957

1. A BLENDED BULKY YARN COMPRISING CONTINUOUS WETSPUN SYNTHETICFILAMENTS INTERMINGLED WITH OTHER CONTINUOUS SYNTHETIC FILAMENTS, SAIDYARN BEING LOOPED AND ENTANGLED AT SPACED INTERVALS ALONG THE YARNLENGTH TO FORM SPACED BULKY SECTIONS IN THE YARN, SAID BULKY SECTIONSBEING SEPARATED FRO EACH OTHER BY AN AXIAL DISTANCE VARYING INCOMPLETELY RANDOM FASHION AND THE BULKINESS OF SAID SECTIONS CONTINOUSLYVARYING IN COMPLETELY RANDOM FASHION, THE MINIMUM VARIATION IN LEANGTHBEING AT LEAST FIVE-FOLD AND THE MINIMUM VARIATION IN BULKINESS BEING ATLEAST TWO-FOLD, THE YARN IN SAID SECTIONS SEPARATING SAID BULKY SECTIONSCOMPRISING SUBSTANTIALLY STRAIGHT FILAMENTS IN COMPACT EVEN ALIGNMENT.